The Gallery of Natural Phenomena

The earth, the sea, the sky - and beyond

Mars has no satellites. Its nights are therefore completely dark, if indeed they are not lit up by aurorae and long lingering twilights.Amedee Guillemin, 1872--------Could we be actually transported to that far distant surface, we should probably find much to astonish us...(but) unity in variety is the universal character of creation.T.W. Webb, 1874--------This very beautiful planetR. S. Ball, 1889--------...there is some reason for believing that MARS may be the abode of intelligent life, or if not at present, may have been in the past an inhabited world.W. Peck, 1890--------What would we learn of Europe if we had only a bird's-eye view of it ...from a height which was a dozen times as far as from the shores of Europe to America?R. S. Ball, 1893--------Looking through the telescope, one saw a circle of deep blue, and the little round planet swimming in the field. It seemed such a little thing, so bright and small and still, faintly marked with transverse stripes, and slightly flattened from the perfect round. But so little it was, so silvery warm, a pin's head of light!H. G. Wells, 1897--------

Mars, April 20th, 1856

Patronising the past has always been a popular pastime. Now spacecraft have flown past, circled or landed upon all the solar system's planets, and those worlds have been viewed in unprecedented detail, the temptation to treat the astronomical efforts of our Earth-bound ancestors with condescension has often proved irresistible. Even their accurate insights are described as 'modern' or 'ahead of their time', as if they must have somehow had access to present-day knowledge, and the idea is often put about that practically nothing was known about the planets before the advent of spaceflight. This is not so. Their dimensions, distances and basic natures were known, but when it came to details, the problems were immense.

The planet Mars is an example. Mars is only half the size of the Earth, and never approaches nearer than 34 million miles. A large telescope may then show it as a disc with an apparent diameter of 23”, that is, slightly smaller than the full Moon seen with the naked eye. Yet Mars was intriguing. Mercury was too close to the Sun, Venus was covered by unbroken cloud, and the planets beyond Mars were obviously alien worlds. Only the Red Planet seemed to show features which suggested that it might be something like the Earth.

Mars, 1865Drawing by the Rev. W. R. Dawes

Galileo, the first telescopic astronomer, turned his optic tube upon Mars, but saw no details. Fontana, in Naples, was the first to see markings on the planet, in 1636, but his 'feeble telescope' was not up to the task of showing more. The first drawing showing a recognisable Martian feature was made by Christian Huygens on November 28, 1659. It depicted a dark triangular region later known as Syrtis Major. In 1666 Giovanni Cassini calculated the rotation period of Mars as 24 hours 40 minutes, only about half an hour longer than that of the Earth. He suggested that the dark areas of the planet were seas and the light areas lands. Could Mars be a smaller Earth?

In 1672, Huygens and Cassini detected a white cap at the Martian poles. This grew and retreated with the seasons on Mars, and thus was, almost certainly, a 'snowy deposit'. By the mid-19th Century, most astronomers were of the opinion that Mars had an atmosphere with clouds, ice caps, oceans and continents. T. W. Webb said in 1874 that only Mars, of all the planets in the solar system, seemed to be “a close relation of our own...arranged in a corresponding manner by the Great Creator as the seat of life and intelligence.”

The south polar cap of Mars, September 8, 1877A drawing by N. E. Green at Maderia

However, Mars was not easy to observe. Victorian astronomers, despite being equipped with telescopes of a quality not known before or since, were restricted to what they could see and draw. Instantaneous photographs of the planets were not possible. Nor did they have unlimited time to study an interesting Martian feature. After half an hour or so, that planet's rotation would have carried it out of sight. Markings could only be seen clearly near the centre of the planet's disc; foreshortening and the obscurity of the Martian atmosphere veiled everything else. During brief moments of good 'seeing', much fine detail was visible; in fact so much that even the best artist could not hope to draw it all in the short time available. N. E. Green, who observed Mars in the clear skies of Maderia in 1877 with a 13-inch reflector, said that all astronomical drawings should be regarded with caution, for “they are necessarily exaggerations. When the eye has been taxed to the utmost to observe the form of some delicate marking, any shade which the hand could apply to a drawing...must be far beyond the strength of the reality.”

Mars, 1888

Some were even less optimistic. Professor Kaiser, of the Leiden Observatory, who examined 412 drawings of Mars, remarked gloomily that many depictions of the planet, even when they showed the same hemisphere, were so discordant that “no-one would believe that they were intended for the same body.” He believed “that the art of drawing celestial bodies is at much too low a pitch to justify accurate deductions as to their physical character”, and thought that we knew nothing certain about Mars but the facts that the planet had an atmosphere and the polar caps varied with the seasons. R. S. Ball pointed out in 1893 that the view of Mars in the best telescopes was more or less equivalent to a naked-eye view of the Earth from a distance of 35,000 miles, and “the smallest object that would be discernible on Mars must be as large as London.”

Observers persevered, and by 1864 a 'pretty correct representation had been attained' of the features in a broad belt round the Martian equator. Maps were made of the dark and light regions, generally believed by most astronomers to be 'oceans' and 'continents'.

There were disagreements. Professor Kaiser pointed out that the borders between the dark 'oceans' and light 'continents' were ill-defined, even when the polar caps showed sharp edges. If the dark areas were seas, then “they cannot resemble seas such as our own.”

The colours of Mars were also a matter of dispute. Were the dark areas green, blue, or (as some said) grey? Herschel II thought they were 'the mere result of contrast', but T. W. Webb disagreed. “No-one who saw one of the great seas” as he did with a 9-inch reflector telescope on April 4, 1871, “could doubt the existence of a beautiful clear blue grey tint...a shading on another part of the disc was of a brownish hue”. The dark 'seas' were also described as 'decidedly greenish', while the light 'continents' were yellowish-red.

Mars compared with the Earth, 1893

There were some facts that could be agreed about Mars. Its axial tilt was about the same as the Earth's, so it had seasons, though much longer than ours, due to Mars’ wider orbit. The Martian summer was 181 days long, its winter 147 days. The Sun appears a third smaller from Mars than it does from Earth, and its light and heat are proportionately diminished. In the Martian dawn and twilight, 'a beautiful pair of objects' would appear in the sky; the Earth and the Moon, about a quarter of a degree apart.

Astronomers were always cautious about their interpretations of the Martian features. The greenish-grey areas were usually described as 'lakes, or seas, or oceans', while the yellow and orange regions were 'islands or continents', “as long as we clearly remember”, Robert Ball pointed out, “that the distinction between land and water on the planet is purely of a conjectural character.”

Writers who summarised astronomical findings for an interested public had to be less circumspect. Their readers wanted facts about Mars, rather than probabilities. In 1890, William Peck wrote that the nature of the markings on Mars “has long been known. The greenish portions...are...large tracts of water, or oceans; and the ruddy parts land, or continents.” The Martian southern hemisphere, like that of the Earth, had more water than the northern, and the winters there were more severe, as the south polar cap was larger. Despite this, the climate of Mars was mild, demonstrated by the seas being frozen only near the poles, and even there the cold was not as great as in our polar regions. The Martian continents were subject to floods and changes of level, for “Mars is a planet not nearly so mountainous as Mercury or our earth.”

Mars has an atmosphere, and the atmosphere holds clouds, although they “cannot be compared with the dense clouds of the Earth.” The polar caps melted and reformed, so upon the Red Planet there must be all the phenomena of rain, hail, and snow. The melting of the polar snows, some astronomers believed, produced great seasonal floods, and the exchange of moisture between the two Martian hemispheres “must give rise to storms of unimaginable violence.”

Mars and one of its moons, 1893

Venus has no moons, the Earth has one, and Jupiter was believed to have four. Therefore, it seemed reasonable that Mars should have two. Many eminent astronomers searched for Martian satellites in vain until 1877, when Asaph Hall, using a 24-inch refractor, discovered two tiny companions. They were named Phobos (Fear) and Deimos (Flight). They were far too small to show discs, but subtle calculations, on the assumption that they were made of the same material as Earth's moon, indicated that Phobos might be about 20 miles in diameter and Deimos 18 miles. In that case, Phobos, 4,000 miles from Mars, would appear from the surface of the planet as a body two-thirds the size of our Moon. Deimos, 14,000 miles away, would be a quarter the size of Phobos.

Was there life on Mars? Many astronomers of the era thought there must be. Others were not so optimistic. R. S. Ball pointed out that “the globe of Mars happens to approach very closely the dimensions and mass of the smallest world on which the continued existence of water would be possible. It would perhaps be going rather too far to say that a world the size of Mars must therefore be the smallest on which life could possibly be supported”. However, it seemed very likely that there was at least plant life on Mars. Possibly, as Lambert suggested, Martian vegetation was red rather than green, thus accounting for the colour of the reddish-brown 'continents'. Others considered the colour to be that of the Martian soil, which might resemble red sandstone. Amedee Guillemin, in 1872, was sure that 'living bodies' peopled Mars, although those bodies must differ “notably from that with which we are familiar.”

Chart of Mars, 1890South at top

In September of the year 1877, the director of the Milan Observatory, G. V. Schiaparelli, using an 8½-inch refractor, announced a remarkable discovery. He claimed that the light Martian continents were crossed by long dark canali (channels, gullies, or canals). The 'canals', whatever they were, must have been at least 60 miles wide to be visible from Earth, and some were thousands of miles long. In 1886 they were independently observed by Perrotin and Thollon in Nice with a 15-inch telescope. In 1888, Schiaparelli said that he “saw the hemisphere of Mars so exquisitely delineated that the canals had all the distinctness of an engraving on steel, with the magical beauty of a coloured painting.”Despite this, many other accomplished astronomers searched for the 'canals' in vain, and the debate over whether they actually existed or were the result of eyestrain was to rumble on until the latter half of the 20th Century.

If the 'canals' did exist, what were they? It seemed unlikely that they could be rivers. A small world like Mars could not possibly require a system of rivers each 60 miles wide and thousands of miles long. Some canals crossed a Martian 'continent' from 'ocean' to 'ocean', which for a river would be impossible. Others thought they might be clefts or canyons in a Martian desert.

Percival Lowell, around 1890, disdained such mundane notions. There was intelligent life on Mars, which had constructed over 700 canals to carry meltwater from the polar snows, and they “were unquestionably planned as an irrigation system...the work of living and intelligent beings.”

Now that our instruments have actually landed on Mars, the 21st Century is privileged to be more certain about the nature of the Red Planet. The mean temperature of Mars is minus 67° F. Summer temperatures may reach 48° F. The atmospheric surface pressure is about 5 millibars, about 1/200th that of the Earth. There are no 'canals’, but Mars does have a canyon 2,500 miles long.When the polar caps melt, or more accurately sublime, after winter, winds of up to 250 miles an hour sweep from the poles and whip up huge dust storms.The blue-green 'oceans' were optical illusions. Mars is a red desert, with darker areas which appear bluish-green by an effect of contrast.Despite this, Mars is still a planet of mystery. It has a surface area equal to that of the Earth (having no oceans), and that surface has barely been scratched.